1. Field of the Invention
The present invention relates to image forming apparatus as electro-photographic apparatus, printer, etc. equipped with developing devices for forming developer images on a photosensitive body by bringing developing rollers to contact/separate to/from a photosensitive body.
2. Description of the Related Art
In an image forming apparatus such as a color copier, a color printer, etc. for obtaining color images according to an electro-photographic system, in order to obtain a full-color image using plural toners in different colors such as yellow (Y), magenta (M), cyan (C) and black (BK), an apparatus has been developed, wherein four developing devices filled with color toners corresponding to colors of, for example, a latent image that is formed on a belt-shape photosensitive body are moved successively in the direction of a photosensitive body and a latent image is developed by bringing developing rollers to contact the photosensitive body and after toner images in respective colors are overlapped each other on the photosensitive body or an intermediate transfer body, the overlapped toner images are transferred on a recording paper collectively.
In an image forming apparatus, wherein developing devices are taken out of the main body of the apparatus for supplying toners and reinstalled in the main body after supplying toners, a technology to take out and replace the developing devices through the top of the main body of the apparatus by moving them in the vertical direction to the photosensitive body is disclosed in Japanese Patent Publication No. 10-58754. Further, a technology to remove/install developing devices through the side frame of the main body by moving them in the horizontal direction to the photosensitive body is disclosed in Japanese Patent Publication No. 2-64577.
However, in the case of the former technology described above, when a copier function is provided, there are an optical device for reading original documents, an automatic document feeder, etc. on the top of the main body and the opening/closing of the main body cover is impeded and therefore, this technology is not suited for use. Further, in the case of the latter technology, when an main body of an apparatus is installed at near a corner of an office or there are materials placed around the main body, the opening/closing of the side frame would be impeded and further, in the case of a system with a finish device provided adjacent to the main body in order for the space saving of the main body, the opening/closing would be impeded.
That is therefore desired that when the developing devices are taken out of the main body of an image forming apparatus, they can be taken out easily and smoothly without impeding the opening/closing of the frame for various restrictions and operability at the maintenance of the developing devices can be achieved.
It is an object of this invention to provide an image forming apparatus wherein developing devices are removed and installed from the main body of the image forming apparatus easily and smoothly and operability at the time of maintenance can be improved.
According to embodiments of this invention, an image forming apparatus is provided. This image forming apparatus comprises an image carrier; a latent image forming unit to form a latent image on the image carrier; a developing device having a developing unit to supply a developer to the latent image by sliding in the direction to contact/leave to/from the image carrier in a main body; a positioning device to maintain the developing device in the operable state in the main body; and a driving device to move the developing device in the direction to contact/leave to/from the image carrier after the developing device is connected to the positioning device by connecting and leaving the developing device to the positioning device by applying a load to the developing device in the sliding direction in the main body. This image forming apparatus is characterized in that a load applied to the developing device is cancelled by he driving device after the developing device is connected/removed to/from the positioning device.
Further, according to the embodiments of this invention, an image forming apparatus is provided. This image forming apparatus comprises a photosensitive body; a latent image forming unit to form a latent image on the photosensitive body; a developing device having a developing roller to supply a developer to the latent image by sliding in the direction to contact/leave the photosensitive body in a main body; a positioning member to maintain the developing device in the operable state to develop in the main body; and a driving roller having an acting unit provided around a shaft for sliding the developing device while in contact with the developing device and a canceling unit which is formed by partially cutting the acting unit and not in contact with the developing device for connecting and disconnecting the developing device to the positioning member by applying a load in the sliding direction to the developing device in the main body by rotating the shaft in the state of the acting unit in contact with the developing device and sliding the developing device connected to the positioning member in the direction to contact/leave to/from the photosensitive body. This image forming apparatus is characterized in that after the developing device is connected/separated to/from the positioning member, the canceling unit is brought to face the developing device by rotating the shaft.
Further, according to the embodiments of this invention, an image forming apparatus is provided. This image forming apparatus comprises a photosensitive body; an image forming unit to form a latent image on the photosensitive body; a developing device having a developing roller to supply a developer to the latent images by sliding in the direction to contact/separate to/from the photosensitive body in a main body; a positioning member to maintain the developing device in the operable state for development in the main body; a housing case to house the developing device; and a housing case moving device that apply load in the sliding direction to the housing case by contacting them to connect and remove the developing device to/from the positioning member and after connecting the developing device to the positioning member, bring the developing device to contact/separate to/from the photosensitive body.